Air blast circuit breaker



Feb. 10, 1942. y L. J. LINDE 2,272,214

AIR BLAST CIRCUIT BREAKER Filed Dec. 22; 1959 Figl.

Inventor: Leonard J. Linda,

by His Attorney.

Patented Feb. 10, 1942 AIR BLAST cmcurr BREAKER Leonard J. Linde, Drexel Hill, Pa., assignor to General Electric Company, a corporation of New York Application December 22, 1939, Serial No. 310,603 7 Claims. (Cl. 200-148) My invention relates to improvements in electric circuit breakers and particularly to electric circuit breakers of the gas blast type.

Recent improvements in the design of gas blast electric circuit breakers have greatly increased the interrupting capacity of breakers of this type. In the operation of gas blast breakers of higher capacity the problem of burning completely and cooling sufliciently the gases from the arc chamber before they are exhausted to the atmosphere has become increasingly difficult and it is accordingly an important object of the present invention to provide an electric circuit breaker of the gas blast type having improved means for insuring the complete combustion and adequate cooling of the gases from the arc chamber before they are exhausted to the atmosphere.

It is another object of the invention to provide an improved electric circuit breaker of the gas blast type of such size and shape that it may be interchanged with v existing oil breakers of the same rating and which, at the same time, is

'capable of operating under severe conditions without'exhausting gases to the atmosphere that will damage equipment or, injure an operator or other attendant who happens to be near the circuit breaker unit during its operation.

Further objects and advantages of the present invention will become apparent as the following description proceeds, reference being had to the accompanying drawing in which Fig. 1 is an elevational view partly in section showing an em-' bodiment of my invention, and Fig. 2 is a sectional view taken along the line 2--2 of Fig. 1.

The invention specifically claimed in this application is also disclosed, inter 'alia, in a copending application, Serial No. 363,325, fled October 29, 1940, by W. K. Rankin for ias blast electric circuit breaker,, assigned to the same assignee as the-present invention and having claims generic to the present invention.

Referring to the drawing, the circuit breaker comprises a fixed contact In including a plurality or spring pressed fingers and a movable contact II which is operated by any suitable mechanism (not shown) through an oscillatable insulating arm I: connected thereto by a crosshead IS. A pin l4 carried near the end of the insulating arm I2 is slidably received in a slot II in the cross-head 13. Fixed contact Hi is connected to one line conductor it while movable contact H is connected to the other line conductor II by means or a sleeve 18 .0! conducting material in which the movable contact is slidably mounted. The conductors are mounted in insulated relation to the breaker enclosing structure. by Suitable bushings 19. The relatively movable contacts in and II are arranged to separate withinan arc confining structure 20 of insulating material. A conduit 2| opening into the interior of the arc confining chamber at one side of the relatively movable contacts is provided to supply a blast of arc extinguishing gas,

rial, such as copper.

such as air, to the arc confining chamber when .the contacts are separated. On the opposite side of the relatively movable contacts a plurality of barriers 22 are arranged to provide an arc chute having a plurality of divergent passages through which different sections of the are are. driven during the interrupting operation of the breaker. The are confining chamber 20 is preferably shaped to fit rather closely over the opposite sides of the movable contact so that the passages formed by the barriers 22 are substantially shut off from the gas blast from conduit 2! when the contacts are closed and are progressively opened during separating movement of the contacts. With this construction, the passages formed by the barriers 22 open at one end at longitudinally spaced points along the path of contact separation and each is adapted to receive the gases from the corresponding section of the arc path. Each of the passages formed.

by the barriers and the walls of the arc confining chamber is provided with a plurality of spaced cooling plates 23 of good heat conducting mate- The circuit breaker construction thus far described, on which the present invention is an improvement, is more fully disclosed and is claimed in the copending application of D. C. Prince et al., Serial No. 303,126, filed November 6, 1939, which is assigned to the same assignee as the present invention.

, The results of tests conducted on a circuit breaker or the above construction indicate that the arc is usually interrupted at. an earl point in the separating movement of the relatively movable contacts. Experience also teaches that the hottest gases emerging from the are chambercome from the passages of the arc chute opening adjacent the fixed contact In and further that these gases often'contain a considerable percentage of unburned combustible gas.

' This latter condition exists, particularly, in circuit breakers where the barriers 22 and the arc confining chamber 20 are formed of material, such as hard fiber, which has a tendency to evaporate under the action of the are. In accordance with the present invention an improved arrangement is provided for confining the gases from the arc chamber until they are completely burned and sufiiciently cooled before the are exhausted to the atmosphere. The improved construction is also designed to utilize to best advantage the available space in an air blast breaker unit which is of such a size and shape that it maybe interchanged with oil breaker units of the same rating as are now in service. As illustrated in the drawing, the gases from the arc confining chamber 20 pass through the passages tormed by the barriers 22 and through an percentage of unburned gases.

opening in the side of an elongated housing 24 of insulating material which extends in a direction generally perpendicular to the barriers 22. The housing 24, which is generally rectangular in cross-section, is closed at one end and at the other end opens into an exhaust tube 25. In the preferred .construction illustrated, the tube extends upwardly so that the hot gases are exhausted in that direction. The interior of the housing is divided into upper passages 28 and 21 and lower passage 28 by baille structure comprising a longitudinally extending partition member 29 and one of the diverging barriers 22 oi the are chute which extends below the other barriers and cooperates with the partition member 29 and the side walls to form the oppositely p g upper passages 28 and 21. The partition member 29 terminates a considerable distance from each end of the housing so that the passages 26 and 28 are in communication adjacent the closed end of the housing and the passages 21 and 28 merge near the open end 01 the housing 24 to form an enlarged and free space or combustion chamber 30 in which the gases from passages 21 and 2! may mix and burn. In the drawing the arc confining chamber 20 and the housing 24 are illustrated as integrally formed. It is to be understood, however, that the entire insulating structure may be fabricated from suitable sheet insulating material.

In order to provide for rapid cooling of'the gases within the housing 24 a plurality of stacks of cooling plates 3|, 32 and 33 are provided in the passages 26, 21 and 28, respectively. As clearly shown in Fig. 2 the metal plates are spaced by suitable projections formed on each face of the alternate plates of each stack. Suitable bolts 34, each of which is provided with a suitable spacing sleeve 35 of insulating material, cooperate with the side walls of the housing 24 and'the partition member 29 to hold the plates in proper position.

The advantages of the construction of the present invention will be better understood from a consideration of the circuit interrupting operation of the breaker. As the relatively movable contacts are separated an arc is drawn therebetween. In timed relation with the separation of the contacts a blast of air, or other are extinguishing gas, is supplied to the arc chamber through the conduit 2|. The blast may be controlled by any suitable means (not shown) such as a blast valve operated by the contact operating mechanism. The are is blown against the edge of the barriers 22 and into the passages formed thereby where it is extinguished and the circuit interrupted. In this interrupting process the arc is first elongated as it bends over the edges of the barriers 22 until it finally divides into serially related sections which are separated by the barriers. After interruption of the arc, however, the gases, and particularly those from the vicinity of the fixed contact In, are highly heated and may contain a considerable As previously pointed out, this is particularly true where the barriers 2| are formed of hard fiber or other insulating material having the property of evaporating sufliciently under the action ,of the are to prevent the ends of the barriers from becoming conductive during the circuit interrupting operation. By the present invention, the gases from the vicinity of the fixed contact Ill are conducted toward the closed end of the housing 24 and then returned to the open end of the housing through two stacks of cooling plates 3i and 33. The gases from the side of the arcing chamber or arc chute remote from the fixed contact are conducted directly to chamber 30 at the open end of the housing 24 through the upper passage 21 where they are mixed with the gases from the lower passage of the housing 24 before they are exhausted to the tube 25. The gases from the upper passage contain a very small percentage of combustible gas and are to a large extent fresh air supplied by the conduit 20. The mixture of the gases from the upper and lower passages in the chamber 30 before they are exhausted to the tube 25 provides for the complete combustion of any unburned gases from the lower passage 28 of the housing 24. Thus it is seen that the hottest gases and those containing combustible gases in quantity are led through a tortuous, circuitous path to a combustion space, while the less highly heated and less combustible gases from that portion of the path of contact travel remote from the fixed contact are led directly to the combustion space where the gases may mix and burn. This division of gases from the arc chamber makes it possible to exhaust gases to the atmosphere from the tube 25 which are not detrimental to the surrounding equipment or dangerous to personnel without utilizing an unreasonable amount of space for handling the gases.

It has been found with the present construction that under the severest operating conditions no flame or exceedingly hot gases are emitted from the upper end of the exhaust tube 25. The construction also takes advantage of all of the available space in a circuit breaker unit of the size and shape required for substitution in the metal clad units which have previously found widespread application in oil circuit breaker installations.

While I have shown and described my invention in connection with a particular form of gas blast circuit breaker, it will be apparent to those skilled in the art that many features thereof are of general application and I intend in the appended claims to cover all modifications falling within the true scope and spirit of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. A gas blast circuit breaker for interrupting power arcs comprising relatively movable contacts, means independent of the interrupting are for directing a gas blast transversely through the arc gap formed upon separation of said contacts. and insulating structure including an arc chute into which the are is driven by said gas blast from said arc gap, said are chute including barriers extending transversely of said are gap and forming passages arranged to be opened to said blast in succession in accordance with separation of said contacts and deflecting baffle means as sociated with said barriers for causing appreciable elongation of the path of the blast gases traversing the initially opened passages prior to exhaust of the gas from said structure as compared with the paths of blast gases from subsequently opened passages, the blast gases from said subsequently opened passages being comparatively cool when the arc is interrupted at said initially opened passages, and means for directing all said blast gases into a common mixing chamber before final venting thereof to atmosphere.

2. A gas blast circuit breaker comprising relatively movable contacts, means for directing a gas blast transversely through the arc gap formed upon separation of said contacts, and insulating structure including an arc chute having barriers extending divergently from said are gap for directing. said gas blast through said are gap and for dividing the are into serially related sections to cause interruption thereof, said barriers being arranged to form passages that are opened to said blast in succession in accordance with separation of said contacts whereby most of the highly heated arc gases incident to the interruption of a short are traverse the initially opened passages, and deflecting means including baflie structure for causing reversal and elongatlon oi the path of the blast gases traversing said initially opened passages prior to exhaust of said gases from said insulating structure.

3. An air blast circuit breaker for interrupting power arcs comprising relatively movable contacts, means independent of the interrupting are for directing an air blast through the arc gap formed upon separation of said contacts for interrupting the arc within a part of the complete opening movement of said contacts, and an insulating structure including an arc chute through which said air blast is directed for receiving and confining the arc during the arc interrupting operation and for rendering harmless the gases that exhaust from said structure, at least a portion of said are chute being formed of material adapted to emit combustible gases when subjected 'to the are heat, means defining passages in said chute leading directly from points spaced longitudinally of the path of contact travel, and baiiie means arranged so that the gases from the blast traversing the first formed part of the arc path are directed along an elongated path and subsequently directed into and mixed with fresh air from the air blast traversing that part of the path of contact travel established'after arc interruption for insuring substantially complete combustion of said gases in said insulating struc ture prior to exhaust to atmosphere.

4. An air blast circuit breakercomprising relatively movable contacts, means for directing an air blast through the arc gap formed upon separation of said contacts for interrupting the are within a part of the complete opening movement of said contacts, and an arc chute through which said air blast is directed for receiving and confining the arc during the arc interrupting operation and for rendering harmless the gases that exhaust from said chute, said arc chute including barriers composed of insulating structure adapted to emit combustible gases when subjected to the are heat, said barriers defining passages in said chute leading directlyfrom points spaced longitudinally of the path of contact travel whereby the gases from the blast traversing the first formed part of the arc path exhaust" through the corresponding passage, and deflecting means for reversing and elongating the path of the aforesaid gases so that they are subsequently directed into and mixed with fresh air from the air blast traversing that part of the path of contact travel established after arc interruption for insuring substantially complete combustion of said gases said chute prior to exhaust. to atmosphere. .2

5. An air blast circuit breaker comprising relatively movable contacts, means for directing an chute through which said air blast is directed for receiving and confining the arc during the arc interrupting operation, said arc chute including hard fibre barriers that emit combustible gases when subjected to the arc heat, said barriers extending transversely of said air gap and in the direction of said blast so as to define passages in said chute leading directly from points spaced longitudinally of the path of contact travel, and a combustion chamber connecting with said passages for mixing said combustible gases with additional fresh air for insuring substantially complete combustion of said gases prior to their exhaust from said chamber, the gases from the blast traversing the first formed part of the arc path being directed through a tortuous path and mixed with fresh air from a fresh air blast passing directly from that part oi the path of contact travel established after arc interruption to said chamber.

6, An air blast circuit breaker comprising relatively movable contacts, means for directing an air blast transversely through the arc gap formed uponoseparation of said contacts for interrupting the are within a part of the complete opening movement or said contacts, an arc chute having it narrow blast entrance opening at which said arc gap is formed and a flared exhaust opening, said are chute including insulating banriers extending divergently' from said arc gap and adapted to emit combustible gases when subjected to the are heat, said barriers defining diverging passages in said chute leading directly from the point of contact separation and also points spaced longitudinally of the path of contact travel, and a housing connecting with the chute exhaust opening, said housing having a baffle for deflecting the blast gases from said point of contact separation along a loop-like path in said chamber and thereafter to mix with fresh air from the air blast traversing by way of a direct and comparatively short passage that part of the path of contact travel established after arc interruption. n

7. An air blast circuit breaker comprising relatively movable contacts, means for directing an air blast through the arc gap formed by the,

tudinally spaced points along the path of conair blast transversely through the arc gap formed upon separation of said contacts for interrupting the arc. within a part of the complete opening movement of said contacts, an insulating arc tact travel whereby the gases from the biast traversing the first formed part of the path or contact travel are directed into the correspond-: ing passage, an elongated housing extending in substantially the direction of contact travel and having an open end and a closed end, said are chute having the exhaust end thereof communi- I eating with the interior of said housing intermediate the ends thereof, said housing including means for deflecting the gases from the first formed portion of said path of contact travel toward the closed end of said housing and back toward the open end thereof, and means for directing the air traversing the latter formed portion of said path of contact travel into said first mentioned gases near the open end of said housing where they are mixed and burned before they are exhausted to the atmosphere.

' LEONARD J. LINDE. 

